Damage Mechanism Evaluation of Large-Scale Concrete Structures Affected by Alkali-Silica Reaction Using Acoustic Emission

Vafa Soltangharaei,Zhongguo Ma,Nolan Hayes,Paul Ziehl,Rafal Anay,Yann Le Pape,Lateef Assi

doi:10.3390/app8112148

Abstract

Alkali-silica reaction has caused damage to concrete structures, endangering structural serviceability and integrity. This is of concern in sensitive structures such as nuclear power plants. In this study, acoustic emission (AE) was employed as a structural health monitoring strategy in large-scale, reinforced concrete specimens affected by alkali-silica reaction with differing boundary conditions resembling the common conditions found in nuclear containments. An agglomerative hierarchical algorithm was utilized to classify the AE data based on energy-frequency based features. The AE signals were transferred into the frequency domain and the energies in several frequency bands were calculated and normalized to the total energy of signals. Principle component analysis was used to reduce feature redundancy. Then the selected principal components were considered as features in an input of the pattern recognition algorithm. The sensor located in the center of the confined specimen registered the largest portion of AE energy release, while in the unconfined specimen the energy is distributed more uniformly. This confirms the results of the volumetric strain, which shows that the expansion in the confined specimen is oriented along the thickness of the specimen.

Highlights

Alkali-silica reaction (ASR) is a chemical processes that has caused damage in concrete structures such as bridges [1,2,3,4], nuclear power plants [5,6,7,8,9], and concrete dams [5,10]
Acoustic emission was utilized for monitoring the activities caused by ASR in large-scale reinforced concrete specimens
An agglomerative hierarchical algorithm was used to classify the Acoustic emission (AE) data based on the energy-frequency dependent features to study and identify the damage mechanisms in the specimens with different stress boundary conditions

Summary

Introduction

Alkali-silica reaction (ASR) is a chemical processes that has caused damage in concrete structures such as bridges [1,2,3,4], nuclear power plants [5,6,7,8,9], and concrete dams [5,10]. The gel expands in humidity exceeding 80% [6] This expansion induces pressure on the concrete matrix and aggregates and causes micro-cracks and cracks when the pressure exceeds the tensile strength of the concrete [11,12]. Several traditional methods such as visual inspection, coring, and petrographic analysis have been utilized for monitoring and identifying the behavior of damage caused by ASR

Methods

Results

Conclusion